1. Field of the Invention
The present invention relates to a bracket assembly.
2. Description of the Related Art
Propeller shafts have conventionally been used as a power transmission member coupling a transmission installed in a vehicle front section and a final reduction gear installed in a vehicle rear section.
When the length of such a propeller shaft exceeds a predetermined length, the critical speed becomes low and might be in a practical range. To avoid this risk, the propeller shaft of more than a predetermined length is divided at an intermediate portion. More specifically, the propeller shaft includes: a first propeller shaft disposed on the front side; a second propeller shaft disposed on a rear side; and a universal joint that couples the first propeller shaft and the second propeller shaft.
In the propeller shaft divided at the intermediate portion, the universal joint disposed at the intermediate portion is rotatably supported by an intermediate bearing structure attached to the vehicle body.
The intermediate bearing structure described above includes: an intermediate bearing fitted onto a shaft portion of the universal joint; a vibration isolation member fitted onto the intermediate bearing; a cylindrical member fitted onto the vibration isolation member; and a bracket that extends along an outer circumference surface of the cylindrical member, and extend toward the outer side in a horizontal direction to be fixed to a vehicle body.
A combination of the cylindrical member and the bracket is hereinafter referred to as a bracket assembly. A portion of the bracket extending toward the outer side in the horizontal direction to be fixed to the vehicle body by being fastened by a fastener such as a bolt is referred to as a leg.
Automobiles have been required to be deformable at a body panel in a front section of the vehicle body including an engine room with a motor and a transmission moved rearward, to absorb impact energy from the front side.
Thus, in some cases, the propeller shaft is configured in such a manner that the intermediate bearing structure is separated (detached) from the vehicle body in response to a head-on collision, so that the rearward movement of the motor and the like is not hampered. In this configuration, the universal joint is bendable with large angle and a steel tube of the first or the second propeller shaft is breakable, whereby the motor and the like can move rearward.
The configuration for separating the intermediate bearing structure from the vehicle body in response to the head-on collision includes the following configurations.
Japanese Utility Model Application Laid-open No. H 04-046925 discloses a configuration where a slit, extending forward from a bolt hole, is formed in a leg of a bracket. A stopper plate protruding toward the outer side in the horizontal direction is formed on the outer circumference surface of the first propeller shaft. When the first propeller shaft moves rearward due to the collision, the bracket is pressed toward the rear side by the stopper plate and the slit is widened, whereby the leg is detached from the bolt and thus the intermediate bearing structure as a whole is separated from the vehicle body.
Japanese Patent No. 4323877 discloses a configuration where a fragile portion is formed on the inner side of the bolt hole in a vehicle width direction, in the leg of the bracket. Thus, a load transmitted to the bracket due to the collision breaks the fragile portion, and thus the intermediate bearing structure is separated, leaving only a part of the leg on the vehicle body.
[Patent Document 1] Japanese Utility Model Application Laid-open No. H 04-046925
[Patent Document 2] Japanese Patent No. 4323877
In many cases, a resin member is disposed behind the intermediate bearing structure. Thus, with the techniques disclosed in Japanese Utility Model Application Laid-open No. H 04-046925 and Japanese Patent No. 4323877, the leg or part of the leg of the metallic bracket might be stuck into the resin member and the resin member might be damaged.
The present invention is made to solve the problem described above, and an object of the present invention is to provide a bracket assembly with which, when an intermediate bearing structure is separated from the vehicle body, a peripheral resin member is less likely to be damaged.